Lathe-center.



. c. s. TOTTEN. LATHE GENT-ER. Ammouou FILED nu 1a, 190g. I @4 1 Patented Aug. L0, i909.

@uw @N NNYTI NN w CLARK s. "Terran, or PITTSFIELD, MASSACHUSETTS.

Lasne-enzima.

` speci-nemen of Lettere Parana Patented Alig 10, 190g.

Appnefi elc .tray 1 3, 196s. serial No. 432,664.

To all whom 'ii may concern:

13e it known that l, CLARK S. ToTTEN, a

citizenI of the United States, residing 'at Pittsfield, in the count of, Berkshire and State of Massachusetts, ave invented a new and useful Lathe-Centcr, of which the followlng is a specification.

This invention relates lto lathe centers, and more to that commonly known as the dead center.

One object of the invention is to rovide an improved general form of roller caring dead center.

Another object ofthe invention isto provide a means of adjusting the movable parts of said centers with' reference to the stationary arts.

Tie invention comprises a tapered shank arranged to be held within the back head of .the lathe and a movable part mounted thereon of improved construction.

vThe invention further comprises such novel details of arrangement and combinations of parts, hereinafter fully described, illustrated i'n the accompanying drawings,

, and specifically set forth 1n the claims.

In the accompan ing drawings, Figure l is an assembly of t e device partly in sections. Fig. 2 is a view of the movable or.-

tion disconnected from the iXed potlom Fig. 3 is a view showing the arrangement of the balls. f

The -invention comprises a collet 10 p rovided with a taper shank 1 1, adapted to fit within the opening of a lathe center.` The collet end is provided with a frusto-conical recess 12, and acylindrical recess -13 leading therefrom. On the -l'ace of the collet and surrounding the frusto-conical recess is a ball race 14.4 There is further rovided in the collet, one or more threaded ateral openings 15. Adjacent the face of the collet there 1s an annular rabbet 16.

- The center properis indicated at 17 and is of the usual conical form. A collar 18 is formed on the center and is of cylindrical' shape. To the rear of the'collar 18, there'is a frusto-conical portion 1 9 of slightly smaller dimensions than the frusto-conical recess 12. This truste-conical portion is extended rearwardly to form a shank 20 having a reduced portion 21, trapezoidalin cross section, the

side walls of the reducedf'ortion being preferably at an angle Vof 1 0" t each' other.l The center '17 is further rovided with aball race' 22 surrounding the ase of the truste-conica portion19. The ball races 14 and 22 are thus brought into juxtaposition and balls 23 are held within these races. The cylindrical portion 18 of the center is of substantially the same' diameter as the rabbeted portion 16 of the collet. On the cylindrical ortion V18 is mounted a ring 24, being held t ereon by means of jscrews 25. `Within Ieach of the threaded openings 15, there is provided a set screw 26 the point ofwhich is beveled to correspond with the angle of the reduced portionV 21 of the center. There is further provide in the said openings va lock screw 27. Itis to be observed that the balls 23 are of such diameter that the portion of the centers designated which lie within the frusto-conical and cylindrical recess` inrthe collet will be held free from said recess; being slightllyr spaced therefrom. Forthe urpose o` oiing the device there is provi ed an oil hole 28 which opens into the space between the frusto-conical recess andl the lf 'rusto-conical portion of the center. It is further to be observed that the threaded openings 15 are -so positioned with reference to the reduced portion 21 of the center when it is in place that the screw 26 will tend to draw the collet and center together. There is thus provided a means whereby the device-may be adjusted in the event of the balls of ball races-being worn.

In the operation of the device, the center is laced in position in the ytail stock of a lat e and the work being properly placed is held in place by the live center and this center with a sufficient degree of pressure to cause a riction between the work and the centers to be greater than'that between the center and the collet.

It is obviousthat minor changes may be made in the form and construction oifthis..

device without departing from the material principles thereof. I do not, therefore, desire to confine myself to theexact form a`nd pro ortion herein shown and described, but wis lto'include all such as 'properly come within the scope of m -inventlonge` i Having thus descri ed thedetice, what 1s claimed'as new is:`a

1. In a device of the class described, a'colf having a shank seatinin s md recess, said shankbeing formed wit anennular channel the 'walls' of which are ofpositely inclined and diverge outwardly ba races 'formed m said collet .and center', balls held in said ball 'let provided with a recess, a retatable center reces, and e'setscrew threaded through the lying within the channel and contacting with the innermost Well of the channel only whereby upon adjustment of the said screw,l

the center Will be drawn inwardly with respect to the collet, the adjustment had being in one direction only.

2. In e device of the class described, e collet, e center heving :in adjustable bearing in the collet, anti-'friction elements interposed between the opposed feces of the collet and center, and e' guard ring carried by the center and exten ing over the meeting ends of .while being' assembled thereon.

the center end 'the collet end surrounding 15 the said ends of the collet, the ring projectin considerably beyond the before mentione face of the center whereby toretein the said anti-friction elements upon the seid fece 20 In testimony that I .claim the foregoing ns my own, I have hereto 'affixed my signature in the presence of -tWo Witnesses.

yLARK s. TOTTEN.

Witnesses:

SCOTT L. JOHNSON, GEORGE LEROY THOMPSON. 

